In order to improve their game, golfers often customize their equipment to fit their particular swing. In the absence of a convenient way to make shafts and club heads interchangeable, a store or a business offering custom fitting must either have a large number of clubs with specific characteristics, or must change a particular club using a complicated disassembly and reassembly process. If, for example, a golfer wants to try a golf club shaft with different flex characteristics, or use a club head with a different mass, center of gravity, or moment of inertia, in the past it has not been practical to make such changes. Golf equipment manufacturers have been increasing the variety of clubs available to golfers. For example, a particular model of golf club may be offered in several different loft angles and lie angles to suit a particular golfer's needs. In addition, golfers can choose shafts, whether metal or graphite, and adjust the length of the shaft to suit their swing. Recently, golf clubs have emerged that allow shaft and club head components, such as adjustable weights, to be interchanged to facilitate this customization process.
One example is U.S. Pat. No. 3,524,646 to Wheeler for a Golf Club Assembly. The Wheeler patent discloses a putter having a grip and a putter head, both of which are detachable from a shaft. Fastening members, provided on the upper and lower ends of the shaft, have internal threads, which engage the external threads provided on both the lower end of the grip and the upper end of the putter head shank to secure these components to the shaft. The lower portion of the shaft further includes a flange that contacts the upper end of the putter head shank when the putter head is coupled to the shaft. This design produces an unaesthetic bulge at the top of the shaft and another unaesthetic bulge at the bottom of the shaft.
Another example is U.S. Pat. No. 4,852,782 to Wu et al. for Equipment for Playing Golf. The Wu patent discloses a set of equipment for playing golf that includes a length adjustable shaft and a plurality of club heads that are designed for easy assembly and disassembly. A connecting rod is inserted into an end of the shaft and a pin retains the connecting rod within the shaft. A locking portion of the connecting rod is configured to extend into the neck of a club head and through a slot in the neck. After the locking portion is extended through the slot, the connecting rod is rotated relative to the club head so that the components are locked together. The neck also includes sloping end surfaces that are configured to guide the ends of the pin to adjacent stop surfaces during the relative rotation between the connecting rod and the club head.
Another example is U.S. Pat. No. 4,943,059 to Morell for a Golf Club Having Removable Head. The Morell patent discloses a putter golf club including a releasable golf club head and an elongated golf club shaft. The club head hosel has a plug containing a threaded axial bore. A threaded rod is retained on the connector portion of the shaft and is threaded into the axial bore of the plug of the club head for operatively connecting the shaft to the head.
Another example is U.S. Pat. No. 5,433,442 to Walker for Golf Clubs with Quick Release Heads. The Walker patent discloses a golf club in which the club head is secured to the shaft by a coupling rod and a quick release pin. The upper end of the coupling rod has external threads that engage the internal threads formed in the lower portion of the shaft. The lower end of the coupling rod, which is inserted into the hosel of the club head, has diametric apertures that align with diametric apertures in the hosel to receive the quick release pin.
Another example is U.S. Pat. No. 5,722,901 to Barron et al. for a Releasable Fastening Structure for Trial Golf Club Shafts and Heads. The Barron patent discloses a bayonet-style releasable fastening structure for a golf club and shaft. The club head hosel has a fastening pin in its bore that extends diametrically. The head portion of the shaft has two opposing “U” or “J” shaped channels. The head end portion of shaft fastens on the hosel pin through axial and rotary motion. A spring in the hosel maintains this fastenable interconnection, but allows manually generated, axially inward hosel motion for quick assembly and disassembly.
Another example is U.S. Pat. No. 5,951,411 to Wood et al. for a Hosel Coupling Assembly and Method of Using Same. The Wood patent discloses a golf club including a club head, an interchangeable shaft, and a hosel with an anti-rotation device. The hosel contains an alignment member with an angular surface that is fixed, by a stud, within the hosel bore. A sleeve secured on the shaft end forms another alignment arrangement element and is adapted to engage the alignment element disposed in the hosel bore. A capture mechanism disposed on the shaft engages the hosel to releasably fix the shaft relative to the club head.
Still another example is U.S. Pat. No. 6,547,673 to Roark for an Interchangeable Golf Club Head and Adjustable Handle System. The Roark patent discloses a golf club with a quick release for detaching a club head from a shaft. The quick release is a two-piece connector including a lower connector, which is secured to the hosel of the club head, and an upper connector, which is secured to the lower portion of the shaft. The upper connector has a pin and a ball catch that both protrude radially outward from the lower end of the upper connector. The upper end of the lower connector has a corresponding slot formed therein for receiving the upper connector pin, and a separate hole for receiving the ball catch. When the shaft is coupled to the club head, the lower connector hole retains the ball catch to secure the shaft to the club head.
Another example is U.S. Pat. No. 7,083,529 to Cackett et al. for a Golf Club with Interchangeable Head-Shaft Connections. The Cackett patent discloses a golf club that uses a sleeve/tube arrangement instead of a traditional hosel to connect the interchangeable shaft to the club head in an effort to reduce material weight and provide for quick installation. A mechanical fastener (screw) entering the club head through the sole plate is used to secure the shaft to the club head.
Another example is U.S. Pat. App. Publ. No. 2001/0007835 A1 to Baron for a Modular Golf Club System and Method. The Baron publication discloses a modular golf club including club head, hosel, and shaft. A hosel is attached to a shaft and rotation is prevented by complementary interacting surfaces, adhesive bonding or mechanical fit. The club head and shaft are removably joined together by a collet-type connection.
Other published patent documents, such as U.S. Pat. Nos. 7,300,359; 7,344,449; and 7,427,239 and U.S. Pat. App. Publ. No. 2006/0287125, disclose interchangeable shafts and club heads with anti-rotation devices located there between.
In some examples, the structure that allows the shaft and club head to be interchanged also provides an ability to adjust the characteristics of the golf club. An example is U.S. Pat. No. 4,948,132 to Wharton for a Golf Club. The Wharton patent describes a golf club that is assembled from a club head and a shaft assembly. The shaft assembly includes a lower end portion that defines an axis that is inclined with respect to a shaft. The lower end portion of the shaft assembly includes a cylindrical outer surface with fluting or spines that engage surface discontinuities in a hosel bore of the club head so that the shaft assembly may be located in different configurations relative to the club head.
Another example is U.S. Pat. No. 4,854,582 to Yamada for a Head Connecting Device in Golf Clubs. The Yamada patent discloses a golf club head that includes a shaft connected to the club head through a setting part, which is a sleeve having an inclined shaft bore. The patent describes how the setting part may be rotated to change the direction of the bore and the shaft so the direction of the head against the shaft varies.
Each of the Wharton and Yamada examples provide limited adjustability. In particular, each provides loft and lie orientations that form a perimetric formation that does not provide any interior positions within the perimeter. FIG. 43 illustrates the orientations provided by a known system having eight available relative positions between a shaft and a club head, with the shaft being inclined at approximately 1.25°. As is apparent from that illustration, no interior positions are provided which deleteriously limits the ability to fine tune the fit of the golf club.
There remains a need in the art for golf clubs with an improved connection that provides a more secure fit with improved adjustability and that is easier to manufacture.